Berlin 2008 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 18: Poster Session I - MA 141/144 (Atomic Wires; Size-Selected Clusters; Nanostructures; Metal Substrates: Clean Surfaces+Adsorption of Organic / Bio Molecules+Solid-Liquid Interfaces+Adsorption of O and/or H; Surface or Interface Magnetism; Oxides and Insulators: Clean Surfaces)
O 18.50: Poster
Montag, 25. Februar 2008, 18:30–19:30, Poster F
Electron confinement in nanostructures on Cu(111) — •Sebastian Wedekind, Guillemin Rodary, Dirk Sander, and Jürgen Kirschner — Max-Planck-Institut für Mikrostrukturphysik, Weinberg 2, D-06120 Halle(Saale)
The deposition of 0.7 ML Co onto the clean Cu(111) surface at room temperature leads to the formation of various nanostructures such as hexagonal and triangular vacancy islands on Cu(111), triangular Co islands and elongated rectangular stripes of Cu bounded by parallel dislocation lines. We study the electron confinement within these nanostructures by the means of scanning tunnelling microscopy (STM) and spectroscopy (STS) at 7 K and observe pronounced spatial modulation patterns in the electron local density of states (LDOS) of the nanostructures. We extract the wave-vector (k) of these LDOS modulation patterns in the electron energy range from −1 to +1 eV to obtain the electron dispersion relation. We obtain a discontinuous, step-like dispersion relation, which indicates wave-vector quantization according to kn=nπ/d, where d is the characteristic length of the nanostructure, and n integer [1]. A parabolic fit through the discrete k-states gives the surface state band edge E0=−0.43±0.01 eV and the electron effective mass m*/me=0.39±0.01, where me is the electron mass. For the Co islands we find E0=−0.08±0.02 eV and m*/me=0.42±0.01. The step-like dispersion relation also identifies the complete eigenstate-spectrum of the confined system.
[1] G. Rodary, D. Sander, H. Liu, H. Zhao, L. Niebergall, V. Stepanyuk, P. Bruno, and J. Kirschner, Phys. Rev. B 75, 233412 (2007)